The present invention relates to a detergent composition and a method for producing the same, having improved cleaning characteristics and improved flow characteristics. Laundry detergents are expected to remove various kinds of soils from fabrics or clothes and to be easily dispensed from their containers. Regarding the removal of soils, among the soils expected to be removed by laundry detergents are oil-based soils including mineral oil, olive oil, wool fat and sebum. Other soils expected to be removed by laundry detergents are stains such as grass, wine, tea, blood, milk, ink and cocoa.
The detergency of detergent compositions largely is based upon their efficacy in removing the above-mentioned kinds of soils from fabric or clothes. It is well-known that while certain types of detergent compositions may exhibit strong detergency against one kind of soil, they may not exhibit good detergency against another.
One approach the art has taken to improve the effectiveness of detergent compositions is by the addition of enzymes such as proteases, amylases and lipases into detergent compositions. For example, alkaline proteases produced by cultivation of strains of Bacillus sp. in suitable nutrient media are widely used in detergent compositions. Examples of such commercial protease products are ALCALASE, ESPERASE and SAVINASE, all supplied by NOVO Industri A/S, Denmark. These and similar enzyme products such as MAXACAL from other commercial sources are active in detergent solutions, i.e., at pH values in the range of from 7 to 12 and in the presence of sequestering agents, surfactants and bleaching agents, such as sodium perborate. ALCALASE is produced by strains of the species Bacillus licheniformis. ESPERASE and SAVINASE are obtained by cultivation of strains of alkalophilic Bacilli according to U.S. Pat. No. 3,723,250, specifically from Bacillus Lentus and Bacillus Subtilis, respectively.
Since about 1928, various cleaning compositions, whether laundry detergents, dishwashing detergents, dry cleaning chemicals, etc., were patented which use two or more different enzymes, such as proteases and amylases, e.g., U.S. Pat. No. 1,660,458 and combinations of two different protease enzymes with an amylase, e.g., U.S. Pat. Nos. 2,607,359; 3,634,266 and 3,741,901. U.S. Pat. No. 4,511,490 discloses only combinations of two alkaline protease enzymes. In February 1982, Amway Corporation offered for sale and placed in public use a detergent incorporating the alkaline protease enzymes ALCALASE.TM. and ESPERASE.TM. available from NOVO, and an amylase enzyme.
U.S. Pat. No. 4,927,558 reports washing tests on mixtures of two alkaline proteases from Bacillus sp. in detergent. The data reported in the '558 patent supports the conclusion that mixtures of two alkaline proteases from Bacillus sp. was only slightly better than the detergency of a single protease.
Further, Japanese examined patent application publication 61-19,679 describes the use in a detergent of a combination of two proteases. The exemplified combination uses alkaline proteases from Bacillus sp., one of them being the alkali protease API-21, derived from Bacillus NKS-21 and also known as KAZUSASE. The data from washing tests do not show any improved detergency over the use of a single protease, but merely that the effect extends over a broader temperature range than that of each protease alone. The mixing ratio of the two proteases is 1:1 on activity basis. Thus, while a detergent additive comprising two alkaline proteases from Bacillus sp. for detergents is known, data showing improved detergency have not been published. Bacillus SP. alkali protease API-21 is the subject of U.S. Pat. No. 4,480,037.
In addition to being expected to remove various kinds of soils from fabrics or clothes, laundry detergents are also expected to be easily dispensed from automatic dispensers which some washing machines have. The current trend toward high density nonionic surfactant loaded powder laundry detergents has created a dispensing problem in such automatic dispensers for many powder detergents. There is a continuing need for a heavy duty, high density nonionic containing laundry detergent which also exhibits good dispensibility from automatic dispensing washing machines.